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CVE-2026-65634— Superlinear CPU denial of service in Erlang/OTP ASN.1 OBJECT IDENTIFIER decoder

Quick assessment

Affected
Erlang OTP
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Inefficient algorithmic complexity in the Erlang/OTP asn1 OBJECT IDENTIFIER decoder allows a remote unauthenticated attacker to cause denial of service by sending a crafted OID during the TLS handshake. The BER OID decoder asn1rtt_ber:dec_subidentifiers/3 in l

CVSS 8.2 · High EPSS 0.25% · P17

Affected Version Matrix 3

VendorProduct Version RangeStatus
Erlang OTP 17.0< * affected
3.0< * affected
84adefa331c4159d432d22840663c38f155cd4c1< 0fe2c02fdc06fab1c63be9db1a7456993d20f838 affected
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I. Basic Information for CVE-2026-65634

Vulnerability Information

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Vulnerability Title
Superlinear CPU denial of service in Erlang/OTP ASN.1 OBJECT IDENTIFIER decoder
Source: CVE Program / CVE List V5
Vulnerability Description
Inefficient algorithmic complexity in the Erlang/OTP asn1 OBJECT IDENTIFIER decoder allows a remote unauthenticated attacker to cause denial of service by sending a crafted OID during the TLS handshake. The BER OID decoder asn1rtt_ber:dec_subidentifiers/3 in lib/asn1/src/asn1rtt_ber.erl and the equivalent PER helper asn1rtt_per_common:dec_subidentifiers/3 in lib/asn1/src/asn1rtt_per_common.erl accumulate a base-128 subidentifier into an unbounded integer using (Av bsl 7) + H per continuation byte. Each shift and addition on the growing accumulator is linear in the number of bits already accumulated, giving quadratic total work in the size of a single subidentifier. The JER helper asn1rtt_jer:json2oid/1 in lib/asn1/src/asn1rtt_jer.erl exhibits the same class of unbounded-integer parsing when decoding a dot-separated OID from JSON. A DER-encoded OBJECT IDENTIFIER with one very large arc (approximately 262 KB of continuation bytes) consumes roughly 13 seconds of CPU on typical hardware. The vulnerable decoder is generated into every ASN.1 module that contains an OBJECT IDENTIFIER, including OTP-PUB-KEY which is reached during X.509 certificate parsing via public_key:pkix_decode_cert/2. This decoder runs before any signature or trust chain verification, so any Erlang service that parses peer TLS certificates is exposed: the default for TLS clients (which always parse the server certificate) and for mutual-TLS servers (which parse client certificates). This vulnerability is associated with program files lib/asn1/src/asn1rtt_ber.erl, lib/asn1/src/asn1rtt_per_common.erl and lib/asn1/src/asn1rtt_jer.erl and program routines asn1rtt_ber:dec_subidentifiers/3, asn1rtt_per_common:dec_subidentifiers/3 and asn1rtt_jer:json2oid/1. This issue affects OTP from OTP 17.0 before OTP 27.3.4.18, OTP 28.5.0.7, and OTP 29.1.1, corresponding to asn1 from 3.0 before 5.3.4.3, 5.4.3.1, and 5.5.2. Whether OTP before OTP 17.0, corresponding to asn1 before 3.0, is affected is unknown.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
算法复杂性
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Erlang OTP 17.0 ~ * cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*
Erlang OTP 3.0 ~ * cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*
Erlang OTP 84adefa331c4159d432d22840663c38f155cd4c1 ~ 0fe2c02fdc06fab1c63be9db1a7456993d20f838 cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*

II. Public POCs for CVE-2026-65634

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III. Intelligence Information for CVE-2026-65634

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Patches & Fixes for CVE-2026-65634 (1)

Other References for CVE-2026-65634 (3)

Same Patch Batch · Erlang · 2026-09-22 · 3 CVEs total

CVE-2026-89422 9.3 CRITICAL TLS 1.3 client skips server authentication when ServerHello carries an unsolicited pre_sha
CVE-2026-68956 7.1 HIGH SSH daemon allocates unbounded idle session channels, bypassing max_channels

IV. Related Vulnerabilities

Same product: OTP
Same vendor: Erlang
Same weakness: CWE-407

V. Comments for CVE-2026-65634

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